This Small Business Innovation Research (SBIR) Phase I project aims to develop a microfluidic-based nitric oxide (NO) sensor to prospectively identify wounds that are unlikely to heal. Each year, over 6 million Americans develop chronic wounds such as pressure ulcers and diabetic foot ulcers. In the U.S. alone, the high prevalence of chronic wounds is a $25 billion economic burden. Currently, clinicians rely on medical history, physical examination, and wound imaging to assess healing progress. A point-of-care device that rapidly identifies a specific biochemical cause for poor healing would allow clinicians to enact proper therapies immediately. Nitric oxide (NO) is a key mediator in all stages of wound healing. As would be expected, wounds deficient in NO heal poorly, and treatments that restore NO bioactivity are able to accelerate wound healing. Recent clinical studies have shown that nitrite concentrations in wound fluid (i.e., a stable end-product of NO synthesis) are able to indicate wounds that are less likely to heal. While promising, nitrite accumulates over time and only provides a history of the wound, giving no indication of real-time NO production that would reflect the current healing trajectory of the wound, nor enabling repeat measurements that could monitor the effectiveness of new treatments. Until recently, direct detection of NO has been tedious, expensive, or sample volume-intensive. Clinical Sensors, Inc. has developed a microfluidic electrochemical sensor that rapidly and selectively detects NO directly in <50 L volumes with nanomolar limits of detection. In this proposal, we aim to assess our sensor's ability to measure NO in simulated wound fluids and validate the sensor's accuracy. After completing this work, we will be well positioned to further develop this product through animal wound models and clinical studies. Once fully developed, our sensor technology will enable clinicians to quickly assess wound status at the point-of-care, select appropriate therapies, and monitor the effectiveness of those therapies over time. Ultimately, our sensor may enable clinicians to quickly assess wound status, choose appropriate treatment plans during patient assessment (i.e., point-of-care), and monitor the effectiveness of those treatments over time.